Saturday, October 27, 2007

Mitchel Lichtman on speed and defense

Over at The Hardball Times, a great article by Mitchel Lichtman investigating the connection between a player's speed and the quality of his defense. It's called "Speed and Defense."

Lichtman estimated every player's speed by using a version of Bill James' Speed Score, but a version that doesn't use defense (to avoid "cheating"). He then checked to see if the faster players played better defense than the slower players.

He found that they did. At every position (except catcher, which wasn't included in the study), fast fielders had a better UZR than the slow fielders. As you would expect, speed was more important for outfielders and less important for infielders. The highest effect was in center field. Here are the numbers. Differences are in runs per 150 games. Remember, this is the difference between fast and slow – players with "average" speed are not included:

After that, Lichtman calculated whether speed is more important in bigger parks than smaller parks. He found that it is.

Fast players improved by 0.9 runs when moving to a small park (from a medium or large park), while slow players improved by 5.0 runs. However, when moving to a *large* park, the fast players improved by 7.6 runs, against only 3.3 runs for the slow fielders.

(Note that all players appear to have better UZRs in small and large parks than in medium parks – Lichtman's article suggests reasons why this might be the case.)

The actual study is very much worth reading ... as far as I can tell, Lichtman's methods, comments, and caveats are all right on. Also, his estimates of the square footage of all fields in MLB might come in useful for other studies.